package O2.basic;

public class Variable {
    public static void main(String[] args) {
        int x = 100;
        System.out.println(x);
        x = 200;
        System.out.println(x);

        float f1 = 3.14F;
        double d1 = 3.14;
        Boolean b1 = false;
        char c1 = 'c';
        String s1 = "China";

        StringBuilder sb = new StringBuilder();

        System.out.println(b1);
        System.out.println(c1);
        System.out.println(d1);
        System.out.println(f1);
        System.out.println(s1);

        boolean bt = true;
        boolean bf = false;
        boolean isGreater = 5 > 3; // 计算结果为true
        int age = 12;
        boolean isAdult = age >= 18; // 计算结果为false

        System.out.println(bt);
        System.out.println(bf);
        System.out.println(isGreater);
        System.out.println(isAdult);

        final double PI = Math.PI;
        double r = 2.0;
        double area = PI*Math.pow(r, 2);
        System.out.println(area);

    }
}
